Comorbid Insomnia Contributes to Brain Changes in Fibromyalgia

Comorbid insomnia exacerbates fibromyalgia-related alterations in the default mode network (DMN), according to a novel clinical neuroimaging study published in the Journal of Pain Research.1

Researchers led by Christina S. McCrae, PhD, of the University of Missouri in Columbia, MO, used functional MRI (fMRI) to study brain activity in the intervals between applications of heat stimuli to the sole of the foot. The study population included 39 women with fibromyalgia and comorbid insomnia; 13 women with fibromyalgia alone served as controls.

Results showed that patients with clinically disordered sleep due to comorbid insomnia had significantly more DMN activity during stimulus-free intervals than those with fibromyalgia alone. Also known as the task-negative network because of its activity during rest, the DMN includes the right cingulate gyrus, medial prefrontal gyrus, left inferior parietal lobule, and the left anterior cingulate.

The findings confirmed researchers' expectations that comorbid disease states have an additive effect on brain function.

"Either one of these [conditions] alone is associated with disrupted brain functioning, but putting them together [shows] there is not only overlap of both diagnoses, but you seem to get an exacerbated or elevated dysfunction,"coauthor Jason Craggs, PhD, assistant professor at the University of Missouri School of Health Professions in Columbia, MO, told Clinical Pain Advisor.

Although chronic pain alone previously was associated with altered DMN activity, the impact of comorbidities was difficult to ascertain before the advent of functional neuroimaging, Dr Craggs pointed out.